Seyidov Yuhannas Mirhasan oglu was born on February 16, 1927 in Nakhchivan. In 1949 he graduated from ASU. In 1956 he received a phD in physics, in 1973 he became a doctor of physics, and in 1977 he became a professor.
In 1953-1960 he worked at the Department of Theoretical Physics at ASU and from 1960 headed the Department of Theoretical Physics at the Institute of Physics of the AAS. From 1966 until the end of his life, he headed the Solid State Theory Laboratory of the Institute of Physics of the AAS.
Y.Seyidov's scientific activity is mainly devoted to the theory of magnetic theory of theoretical physics, phase transitions of solids physics and application of quantum field theory.
Y.Seyidov is the author of more than 120 scientific articles. Under his guidance 2 doctors of sciences and 8 doctors of philosophy were trained.
In 1986 he was the winner of the State Prize of the Azerbaijan SSR.
Corresponding member of ANAS Yuhannas Seyidov died in 1996 in Baku.